A Flexible Stent with Small Intestinal Submucosa Covering for Direct Intrahepatic Portocaval Shunt: Experimental Pilot Study in Swine Mahtab Niyyati, Bryan D. Petersen, Dusan Pavcnik, Barry T. Uchida, Hans A. Timmermans, Takao Hiraki, Reng-Hong Wu, Elias Brountzos, Frederick S. Keller, Josef Ro ¨sch Dotter Interventional Institute, Oregon Health & Science University, L342, 3181 SW Sam Jackson Park Road, Portland, O Abstract The suitability of the flexible sandwich Zilver stent-graft (SZSG)with a biologically active tissue layer (smallin- testinal submucosa) for creation of the intravascular ultra- sound (IVUS)-guided direct intrahepatic portocaval shunt (DIPS) was explored in six young swine in a search for a flexible system to replace the rigid polytetrafluoroethylene (PTFE) stentoriginally used by this group with limited success. The portal vein was punctured from the inferior vena cava through the caudate lobe of the liver using IVUS guidance. After balloon dilation of the puncture tract, DIPS was successfully created in all animals with use of an SZSG 9 mm in diameter and 6 cm or 8 cm long. Only one DIPS remained well patent at 14 days when the animal had to be killed because of encephalopathy. DIPS in the other five animals were found to be either severely stenosed (3 ani- mals) or occluded (2 animals) at 4 weeks due to accelerated formation ofneointimal hyperplasia (NIH) in the liver parenchymal portion of the shunt and superimposed thrombosis. The lack of high pressure in the portal system contributed to early endograft closure. The flexible stent and the covering fail badly. The reason for this could be due to either component. More work is required to find a reliable flexiblesystem with long-term patency. Exploration of the IVUS-guided direct extrahepatic portocaval shuntis suggested. Key words:Biomaterials—Endovascular stent-graft, In- terventional treatment—Portal hypertension—Portocaval shunt—Small intestinal submucosa The direct intrahepatic portocaval shunt (DIPS) is a modi- fication ofthe conventional transjugular intrahepatic por- tosystemic shunt (TIPS) with puncture of the portal syste done directly from the inferior vena cava (IVC) through t caudate lobe of the liver. The liver parenchymal tract is k open,after its dilation, with a stent-graft. DIPS has several advantages compared with TIPS [1–3]. In DIPS,the punc- ture of the portal system is done under intravascular ultra- sound (IVUS) guidance and, therefore, is simpler and safer than the blind TIPS puncture. The elimination of the hepa vein from the shunt also eliminates hepatic vein stenosis with the use of bare stents and potential Budd-Chiari syn- drome with use of stent-grafts for TIPS. The short, straight tract through the caudate lobe of the liver may also favo ably influence patency compared with a longer TIPS trac [4,5]. DIPS has been done with rigid balloon-expandable sten grafts and has required their exact positioning in the liver tract,especially avoiding placing the open ends of stent- grafts against the opposite IVC or the portal vein walls. T use of flexible stent-grafts capable of adapting to the vas cular anatomy of a shunt could be an advantage for DIPS just as it is with TIPS, where most of the shunts are creat with flexible self-expandable stents. Several endograft coverings have been tested in TIPS the hypothesis that they might improve shunt patency by separating injured hepatic parenchyma from the blood fl in the shunt. Of the synthetic materials tested, only the Correspondence to: DusanPavcnik,M.D., Ph.D.; email: pavcnikd@ ohsu.edu ª Springer Science+Business Media, Inc. 2005 Published Online: 9 February 2005 Cardio Vascular andI nterventional Radiology Cardiovasc Intervent Radiol (2005) 28:215–220 DOI: 10.1007/s00270-003-0261-0